IT system
IT stelsel
Also known as: it, it-stelsel, it-net, isolation-transformer, separatietransformator, insulation-monitoring, imd, zone-1, zone-2, transformator, transformatoren, isolatietransformator, scheidingstransformator, transformer, atex, explosiegevaar, explosive-atmosphere, ex-zone, iec-60079, brandbaar-gas, flammable-gas, medisch-it-net, operatiekamer, medical-it, groep-2-medisch, felv, selv-pelv-felv, functional-extra-low-voltage, it-stelsel-eerste-fout, imd-alarm, isolatiebewaking, insulation-monitoring-device, medische-ruimte-groep-2, operatiekamer-stelsel, mto-transformator, medisch-it-stelsel, vfd-condensator, dc-bus-ontlading, capacitieve-ontlading, wachttijd-vfd, medisch-klasse-i-eis, mto-egb-klasse-i, it-net-operatiekamer
Power system not (or via high impedance) earthed. First earth fault does not trip; requires insulation monitoring. Used in clean rooms, laboratories, and critical industries.
Practical example
In an operating room, power remains on during a first earth fault thanks to the IT system, while insulation monitoring triggers an alarm for maintenance.
Common mistake
IT system: A second earth fault may persist because the installation 'still works' — a double fault in an IT system still causes a dangerous short-circuit current.
See also
Related terms
In-depth guides
- → Earthing and earthing systems (TN, TT, IT)
- → NEN-EN-IEC 61557-8 IT system and insulation monitoring (IMD) — first-fault detection
- → §411.6 IT system — disconnection on a second fault (§411.6)
- → §414 SELV, PELV & FELV — the extra-low-voltage measure
- → §411.5 (IEC 60364-4-41) The TT system — why an installation's own earth electrode makes an RCD mandatory
- → §131 Protection Principles
- → §411.3.2 Automatic disconnection of supply (AUV)
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